1. Field of the Invention
This specification relates to a liquid crystal display device, and more particularly, to a Line On Glass (LOG) type liquid crystal display device.
2. Related art of the Invention
A Liquid Crystal Display (LCD) device is a display device which is capable of displaying a desired image by supplying data signals responsive to image information to individual pixels having a matrix arrangement and adjusting light transmittance of such pixels.
The LCD device includes a Liquid Crystal (LC) panel having pixels arranged in the form of a matrix, a backlight disposed below the LC panel to emit light, and a driving unit located at an outer periphery of the LC panel to drive the pixels.
The LC panel includes a Thin Film Transistor (TFT) array substrate and a color filter substrate bonded to each other to face each other so as to maintain a cell gap therebetween, and an LC layer located within the cell gap between the TFT array substrate and the color filter substrate.
Here, the LC panel having the array substrate and the color filter substrate bonded to each other includes a common electrode and a pixel electrode so as to apply a magnetic field to the LC layer.
Hence, when a voltage of a data signal applied to the pixel electrode is controlled after a voltage is applied to the common electrode, liquid crystal molecules of the LC panel rotate by a dielectric anisotropy according to the magnetic field between the common electrode and the pixel electrode, so as to transmit or block light for each pixel, thereby representing text or image.
The driving unit includes driving Integrated Circuits (ICs) for applying a gate signal and a data signal to the LC panel. The LCD devices are divided, according to a method of packaging the driving ICs on the LC panel, into a Chip On Glass (COG) type, a Tape Carrier Packet (TCP) type, a Chip On Film (COF) type, and the like.
Among others, the COG type is to adhere the driving IC directly onto the array substrate of the LCD device and connect an output electrode of the driving IC directly to a line pad of the array substrate. The COG type has a simple structure, and accordingly is advantageous in view of a simplified process and a low fabrication cost.
The COG type LCD device is requiring for a method of reducing a resistance of a line of the driving unit, and also a method of maintaining a function of the line of the driving unit against corrosion and external scratches. That is, the line of the driving unit is a core element for driving a screen of the LCD device but exposed to an external environment, which causes a broken fault due to corrosion and external scratches.